Manufacture of carbon bisulphide



Patented Dec. 27, 1938 PATENT oFF-1 MANUFACTUREOF- CARBON-BISULPHIDEHenry;v Merriam,rWest Orange, N. Jassignor to:. General: ChemicalCompany,.-. New- York, N.',.Y.', a corporation .of New York ApplicationSptembel'rZS, 1936,'SerialiNo. 103,126

i form of f sulphur=- dioxidelf gas;Y and #solid icarbonaceous-materia-'l' I Production s of-cafrbony bisulphide` fromsulphur dioxide land sol-icl carbonaceous 'material suc-h aswoodF-*charcoalhasfheretofore been' suggested; Acid sludgesconstituting=fwasteproducts lof'v oil reningf processesin whichlsulphu'ricf ac-idizis r-used may; beedecompos'edbyflieating to'produce-rela-v tively l large amounts Vofs'ulplourv dioxideg'as andsubstantialv quantities-- ci" solid carbonaceous coli-like-'residuessAcid sludgeV coke containing little or'fnov volatile matterf isaparticularly active type ofi carbonaeeousmaterial and may -be usedas--A`a sourcefofffcarbon in the r`manufacture of carbon bisulph'ida1 Inf thepast; carbon bisulphidehas beenA commonlyf prodced'l by; reactingsulphur-vapor and YWood charcoal atf high temperatures', e. g. around1550216566 in` externa1ly1- heatedi4 pots-'orf retorts These retorts arepear-fshapedj` andsmall; being generally@ not more-thanaboutil'inchesiin diameter. `It has been impractical fto 4make the'-retortslmuch larg en because the high externall tex'nperaturesl re#quired toforcethe-necessaryeheat:lto the center offthe reactionfma'sslwouldifb'e' prolfibitive.v The retorts have` been; madel ofcast'ironand..` are relativelyE shortiliv'edon account off thefdeteri` oratingveffects i: of-' the hightemperatu'resfV exter-Vnallysappliedrandtlieacorrosive effects of vsulphurand-Tearbonbisulpliideproduced Furthermore, large` numbersf of such;retorts` arerequired# to obtain any substantial production of product;Gbnsequently,. installation and maintenance costsare highgretortizreplaeements constituting a: considerable: portion. of?operating costs:-4 On account?. of. the endotherrnic natureV lofi thereaction:` of". carbon and'-I sulphur, Whether they sul-'-phurisusuppliedxas sulphur vaporl-or `as sulphur dioxide; supply.' ofh'eat; to i the reaction is: a problema. always: involved;-

O'nee'fofithe': principal objectsof the present inventionz iswtouprovideV rior-1f the` dn'ianufacture of carbon bisulphidefromf.sulphur;l principally as sulphur-Ql dioxide. gas; andffrom solid?carbonaceousr; material bye-faw method? by' which rsulphur dioxidegases=`.and" acidi-sludge* cokes; both derivedfr'om Waste material suchas acid sludges, may beusedto,advantagelaseisourcesaofsulphur andcarbon. Another. objectof..,theinvention:is tor;y provide.a:.methodiby:v which therv heat-,1. neces? sary to, carry, out theendothermicfreactioneot (CL v 23-206) sulphur and carbonl and' by whichheatA losses by radiation-may besuppliedbyburning brimstone; therelatively vlarge amount of heatv gen,- eratedvbeing usedfto satisfythe-- heat requirementsof'- the sulphur-carbon reaction andtooi'setradiation losses; and the sulphur dioxide formed by burning thebrimstone being simul-v iaa'neouslg'r` utiliiedi! intheY process asr asource oiif'sulphur;` AEv fu'rtlier-v` object of 1 the A invention is#toffovercomef tl'edisadvahtages mentioned abovejinf connection fvvith-`apparatususually employed Iin rtheimmufacture of carbon lbisulphide;The-invention .provides processes by which Waste materialssuch^fas-lacidl sld'ges" may-be used'l as Ysoilirciesi'voffl'fsalph'urand? carbon;v by: which heat sulpl-run'dioxi'deifgas is.l .cooledlandthere is-proy ducedzf-:a-:a gaselimixturezfhaving; azi sulphurdioxide concentrationi of: upwards of5'sayc85.%f. In* an otherinapparatus.y unity. elementalflv sulphur is burneclf preferably;V Withfino?.l more thanl enough ainl toe-supply: oxygeni suicient-ito Loxidizethe sulphur: tof; sulphurl dioxide. Combustion'.y of fsulphurrunder these :conditions-r generates; a@ large amountzcfvexcesssl'ieat: In: accordance with the invention, :the amounttof'sulph'urs'b'urnedv2` is :such ase to generateeheatenough solthat;Whennthe hotcombustionfproducts:of'fthe sulphur` burning operation:areftfmixed; with;'concentratedAV sulphur dioxide? gas! from3 the: acid?sludge'Y decomposing unit, the? resulting; gas mixture'.` contains suf'-cent famounti'- ofi` 'lieat so; that: whenl such mix"- ture isintroduced finto i a reduction -Vzoneltotreact carbonandfssulphurrdioxide toy produce carbon-bisulphide i enough ,heat fis:brought into J the reduc# tion zone fto.A maintain the; endothermicreaction c and :oisetf radiation z losses. The` gaseous'` prod= ucts:off: thefreductionf, reaction: are:v cooled,` and thee carbon:bisulplfxid-e` produced 1I is. recovered.'

Thee natinef.` ofi the: invention; operating details,\ objects'andfziadvantages thereof? mayfbe more rfullyl'v un'derstoodi, fron'rkthee followingadscription.:v taken` in lconnection: Withthef' accom-ypanyingg;drawing.,imwhich I o Eiggdc is andiagramrn'atic."villustration'- of vla plant:` Iayouttand Fig. 2 is a vertical section ofan individual reaction chamber.

As indicated, concentrated sulphur dioxide gas and the carbonaceousmaterial preferably used in the process of the invention as sources ofsulphur and carbon are preferably sulphur doxidergases and acid sludgecoke obtained by decomposition of sulphuric acid sludges constitutingwaste products of oil .rening processes. Referring particularly to thesulphur dioxide and acid sludge coke production unit of the plant layoutof Fig. i of the drawing, Ill indicates a sludge decomposing retort. Theparticular construction of the retort is no part of the inventionalthough the sludge is preferablydecomposed in the absence of air orother diluting gas by external heating. Retort l0 may consist forexample of a iixed drum or chamber extending through furnace setting andmaybe equipped with rabbles or a screw conveyor by which the coke formedduring decomposition of the sludge is continuously discharged fromretort l0 through an outlet I2 and collected in azccke storage chamberI3. A rotary kiln may be employed if desired. Acid sludge may befedVfrom tank |13 through pipe l5 containing a suitable control valve.

One end of gas conduit I6 opens into the interior ofthe sludgedecomposing chamber and affords means for conducting the gasesand vaporsgenerated by decomposition of the sludge into the bottom of the coolingtower i7.. The latter may be a vertical cylindrical vessel provided atthe top with a spray arranged to create in the tower a downwardlyflowing spray of Awater or other cooling liquid introduced through pipevI 8. Water and condensate run` out of the bottom of the towerV throughan outlet pipe into Va receiving tank 20. After rising through thetower, in countercurrent flow to the cooling liquid, the cooled sulphurdioxide gases are discharged from the top of the tower into gas line 2|'connected to a drying tower 22. Air employed to support combustion ofsulphur in a subsequent stage ofthe process is introduced ahead of thedrying tower through an inlet 24 having a .control valve 25. V

V tion chamber being Vregulated by adjustment of 'As illustrated in Fig.2, reduction chamber 50 comprises a vertically elongated steel shell 5|provided with a lining 52 of suitable refractory material such asfirebrick. In the lower end of the reaction chamber is aperforated arch54 affording support for a bed 55 of charcoal or coke of substantialdepth. Solid carbonaceous material as from coke storage chamber I3 isfed into the top of reduction chamber 50 from hopper 51 by an air-lock58. Carbon bisulphide, gases and other vapors formed during the reactionare discharged from the reaction chamber through pipe 59 and flowthrough cooling loop 60 into heat transferrer 3|. The reaction gasespass thence through pipe 6| into a cooler 64; The vapor outlet pipe B9of cooler 64 opens into the bottom of an absorbing tower 10 over whichan.absorb ent oil is circulated. I'he eluent oil o1' tower 10 runsthrough line 1| into a still 'I3 provided with a steam connection 15.Vapors from still '|3 flow through pipeV 18 into Vcondenser 18.Absorbing oil discharged from still 13 runs into a cooler 19 and isrecirculated over tower 10 as by pump 8|.

In carrying out the process of the invention, relatively concentratedsulphur d1oxide, produced in any way, and wood charcoal maybe used asthe source of sulphur and carbon, although it is preferred to useconcentrated sulphur dioxide gases and acid sludge coke which may beproduced in the sludge decomposing unit shown in Fig. 1 as follows: Y

sulphuric acid sludges, resulting from refining of oils, vary incomposition. One representative sludge was found to have a titratableacidity of about 50.8% expressed as H2S04, and yielded onV decompositionby destructive distillation about 28% residual coke, and a retort gaswhich, after cooling to Vabout normal temperatures, produced about 6%condensable oils, about 35% water, based on the weight of the sludge,the balance of the retort gas comprising sulphur dioxide, carbondioxide, carbon monoxidanitrogen, and uncondensable hydrocarbonsandwater vapor. Although the invention isnot dependent upon anyparticular method for the destructive distillation of sludge material,derived from sulphuric acid rening of oils, to produce sulphur dioxidegas and sludge coke, decomposition of thesludge is preferablyl effectedby externally heatinga body of sludge, Yin a substantially air-tight,elongated kiln or retort, mounted in a furnace setting andV arrangedtoprovide for feed of sludge into and withdrawal of sulphur dioxide'gasesfrom one end, discharge of residual coke from the other end, andmaintenance of the higher temperatures at the coke Ydischarge end andlowertemperatures Y at the sludge inlet end. The burners in the furnacecombustion'chamber are controlled so as'to maintain sludge materialtemperatures in the retort not less than about 300 F. at the cold endand not more than about 700 F. at .the hot end. Itis preferred tomaintain temperatures of about 325 F. at sludge inlet end and about 450"F. V at coke discharge end. .On heating, the free and combinedYsulphuric acid contained in the sludge is reduced by hydrocarbonsand/or by the carbonaceous matter present inthe sludge, and

the gas mixture evolved contains sulphur dioxide and water vapor, asthe-major constituents, together with smaller quantities of hydrocarbonvapors, carbon dioxide, carbon monoxide and nitrogen. Y

As a rule, Vdecomposition of the sludge is effected at temperatures suchas above noted, and under such conditions that decomposition proceedsonly to approximately a point at which most of the free and combinedsulphuric acid initially .contained in the sludge is reduced. Underthese conditions, the solid carbonaceous Vresidues formed usuallycontain appreciable Y Per cent Total acidity VHzSO4, 2.1 Ash 1.2 Totalvolatile matter, including II2SO4 32.1 Fixed carbon v 66.7

Y am

`If rdesired, decomposition of the-sludge may be carried out so thatmost of the volatile matter is driven out 'of the coke-although it ispreferred to proceedI as `described to avoid formation of a relativelylarge amount of non-condensable hydrocarbons "which tend to increasehydrogen sulphide formation in the subsequent carbon bisulphideproduction stage.

'-I-hegases formed in retort i0 by decompositionlof the sludge anddischarged into pipe connection I6 contain generally not substantiallyin excess of by Volume of sulphur dioxide, around 'I5-80% water vapor,and smaller quantities of hydrocarbon vapors and carbon. dioxide. Theretort-gas flows. through line I6- intocooling tower I'l `and iscontacted therein with a down- -Wardly flowing stream of waterintroduced through pipe t8. The gas stream rising through the Vtower iscooled, and the bulk of the water and condensablc hydrocarbon vapors ofthe retort gasf stream areco-ndensed and run out of the tower with thecooling liquid into tank 20. The quantity of water run through the towervis. regulated so as -to cool the sulphur dioxide gas to about 100 F. atwhich temperature the gas stream enters the gas line 2l and is conductedinto drying tower 22.

The gas in conduit 2l is a concentrated gas `and may contain 85 topractically 100% SO2. Where the gas contains less than 100% SO2 thediluents comprise small quantities of CO2, CO, N2 and hydrocarbons.Although it is preferred to use 'strong sulphur dioxide gases of thetype mentioned, weaker gases may be vemployed if desired.

Byadjustment oi valve 25, the quantity of air required to supportcombustion of sulphur in sublimer 40 is introduced into pipe 2 i, andthe combined mixture of sulphur dioxide gas and air lis introduced intothe bottom of drying tower 22 which may be operated the same as dryingtowers well known in the sulphuric acid art. Substantially completedrying of the gas is desirable since hydrogen combines with sulphur thusincreasing sulphur losses as H28 in the subsequent vreduction process.The effluent gas of the dryingtower, at temperatures of about 100 F.runs lthrough line 30 into transferrer 3l in which the gas is heated byheat transfer from outgoing hot reaction products totemperatures ofabout Sublimer 40 is preferably of the type in which .a relatively smallamount of sulphur is burned tof lsulphui dioxide, and the heat generatedis `utilized to vaporize the balance of the sulphur in the sublimer. Thesulphur dioxide and the sulphur vapor produced in the sublimer are thenfed into a combustion chamber in which the sulphur vapo-r is burned tosulphur dioxide. In the preferred form of the process, the amount of airintroduced into the system by adjustment of valve 25 is not more andpermissibly less than enough to burn all of the brimstone employed inthe process to sulphur dioxide. It is not desirable to introduce intothe system a quantity of air such that there might be some free oxygenin the exit gas of the combustion chamber, since the presence of freeoxygen in the gas increases the COS, CO2 and C0 content of the reductionVchamber exit gas. Since only a part of the sul- '.phurintroduced intosublimer $2 is burned there- -inlto sulphur dioxide, only enough air forthis purpose is passed into the sublimer. Accord- -.ing`ly, Valve 45.isadjusted so as toper'mit introduction into the sublimer of a sufhcientamount ofthe air-sulphur dioxide gas mixture in line 34 to supplycxygeni enough to burn the desired limited quantity of sulphur insublimer 40. The amount of oxygen introduced into the sublimer throughpipe 35 in the form of air is of course dependent upon the quantity ofsulphur used in the process. When working with a gas of the naturedescribed, the air-sulphur dioxide gas mixture in pipe 34 may be splitby adjustment of valves All and so that approximately one volurne of thegas mixture f line 3d enters sublimer lii thro-ugh pipe 35 to abouteight to ten volumes of gas entering combustion chamber through pipe 36.

The eiiluent gas mixture of sublimer 0 containing for example about 23%sulphur dioxide and about 18% sulphur (calculated as Ss) vapor is fedinto combustion chamber ll in which the sulphur vapor is burned tosulphur dioxide. Since as indicated above there is no more airintroduced into the system than is necessary to burn the sulphur dioxidethe brimstone fed into the sublimer, Vburning of such brimstone producesa gas containing approximately 21% sulphur dioxide, 79% nitrogen and nofree oxygen. Burning of the sulphur under these conditions generatessuicient heat to raise the temperature of such 21% SO2-'79% nitrogen gasas high as about 300D-3300" F., which temperature is much in excess ofthe 150G-1600" F. reaction temperature required in reduction chamber tocause reaction of sulphur dioxide and carbon to produce carbon bisulde.In accordance with the invention, the excess heat developed by burningthe sulphur is utilized to heat up to reaction temperature the coldstrong sulphur dioxide gas introduced into the system throughpipe 2| Thequantity of brimstone burned in the process is dependent upon speciiicoperating conditions and radiation loss. In accordance with theinvention, the quantity of brimstone introduced into the system andburned to sulphur dioxide is. such as to produce heat enough so that,when the hot sulphur dioxide gas produced by burning of sulphurpreferably with not more air than to oxidize the sulphur to sulphurdioxide is mixed with the cold incoming sulphur dioxide gas of whateverconcentration, the temperature of the resulting gas mixture issufficient to carry into reduction chamber 50 heat enough to maintainthe endo-thermic reaction and to offset radiation losses in the system.

For example, when working under the preferred conditions, i. e.introducing into the system no more air than necessary to burn tosulphur dioxide the brimstone fed into the sublimer, about 1.88 lbs. ofbrimstone burned with about cubic feet of air produces a gas comprising21 cubic feet SO2 and '79 cubic feet of N2 and heated .to temperature ofabout 3000 F. About 1 lb. of sulphur (as SO2 from the. sludge gas) isequivalent to about 2 lbs. of sulphur dioxide giving about 11.2 cubicfeet of approximately 100% .f

SO2 sludge gas at a temperature of about 100 F. The latter gas is mixedwith the 21 cubic feet of SO2 and the 79 cubic feet of N2 (produced byburning brmstone) giving a gas entering reduction chamber 50 containingabout 29% SO2 and l about 71% N2, the temperature of such gas mixturebeing about 3000 F., (taking into consideration the approximate 700 F.of `preheat contained in theincoming sludge SO2 gas and-airobtainedbypassage through Ithe heat-exchanger x75 3|). On the basis Vofthe foregoing, the composition of gas leaving reduction chamber. 50 maybe approximately as follows:

It is noted that no operating dinculties are encountered by regulatingthe amount of air introduced into the system to only that necessary tooxidize the brimstone to sulphur dioxide. In fact under somecircumstances, in' order to insure the absence of free oxygen in theexit gas of the combustion chamber, it might be desirable to operatewith a deficiency of air since any unburned sulphur' vapor passes alongthrough the combustion chamber 4l and pipe 48 into reduction chamber 50,and the sulphur as such reacts with the carbon to produce carbonbisulphide.

When carrying out the process of theV invention, in order to obtain ahigh yield of carbon bisulphide under most economical conditions, it ispreferable to use in theV reaction chamber 50 sludge material coke fromwhich the volatile matter has been expelled by heating to temperaturesof 14100-1500" F. for a suicient period of time to drive substantiallyall of the volatile matter out of the coke or in any Ycase to reduce thevolatile matter of the coke to not more than about 3%. When followingthis procedure the coke from bin I3 is so treated and then utilized inreduction chamber 5U.

At the high temperatures prevailing in the reaction chamber 5 by reasonof the heat brought in with the hot sulphur dioxide gas, carbon andsulphur dioxide combine to form carbon bisulphide vapor which leaves thereaction chamber through pipe 59. Gases'in pipe 59, at temperatures ofsay 1550-1650 F., and which may be of the composition above noted, flowthrough loop 60 and are cooled down to about 1106 F. at whichtemperatures the reaction gas stream passes through transferrer 3i, theheat of the reaction gases being transmitted to the cold sulphur dioxidegas. If desired,V transferrer 3l may.V be made of an alloy of high heatresisting properties and the hot exit gas of the reaction chamber 50 maybe introduced directly into transferrer 3l, thus imparting more heat tocool incoming gases and reducing the amount of sulphur burned in thesystem. Th-e reaction gases cooled to about 500 F. pass through line 6Iinto cooler or condenser 54 in which the vapors are cooled to aboutnormal temperatures. Residual gases of condenser 64 contain COS andappreciable amounts of CS2 Vapor. These gases are then passed into thebottom of tower over which an absorbent oil such as straw oil iscirculated. The oil absorbs the Carbon bisulphide which has escaped fromthe condenser 64, and the effluent oil of tower 10 runs through line 1|into the still 13. Steam from line is introduced into the latter andcarbon bisulphide is vaporized and passes through line 16 into condenser18. The temperature of the oil discharged from still I3 is reduced'to'about'100 F. in cooler 19 and is again passed over absorbing tower'l0 by pump 8l.VV The exit gases of tower 10 may be vented totheatmosphere or treated as desired to recover sulphur values.

'The principles of the invention, involving heat supply to asulphur-carbon reaction zone by burning sulphur in the main incoming gasstream, are applicable to modifications other Vthan that just described.For example, brimstone may be burned with less oxygen or air than isnecessary to complete combustion of all of the brimstone, thus producinga gas mixture containing SO2, sulphur vapor and no free oxygen. Whensuch gas mixture is passed into the reaction chamber the sulphur vaporand the sulphur of the SO2 react with the carbonaceous material to formCS2. In this modification it will be understood the amountV of brimstoneburned to SO2 is regulated so that the resulting gas mixture passinginto the reaction chamber contains a sufficient quantity of heat tomaintain the endothermic reaction'.

f desired, brimstone may be burned under conditions such thatVsubstantially all of the sulphur is oxidized to a sulphur dioxide gascontaining preferably no free oxygen, and heat over and above thatneeded to maintain the carbon bisulphide production reaction removed byany suitable means prior to introduction of the gas into the reactionzone. According to another modified procedure, sulphur may be melted andVaporized b-y external heat, for example by burning coke obtained fromthe decomposition of acid sludge. A preferably dry mixture of sludgesulphur dioxide and air in quantity suicient to burn the sulphur vaporto sulphur dioxideV and nitrogen may be introduced into combustionchamber il where theV vaporized sulphur is burned. By proceeding in thismanner, the additional heat supplied by the external source makes itpossible to use about twice as much sludge sulphur dioxide'as in thatform of the invention discussed inV connection with the'drawing.

The invention thus provides a process in accordance with which sulphurdioxide and coke both obtained from waste material such as acid sludgesmay be utilized as sources of sulphur and carbon in the production ofcarbon bisulphide. The extraneous heat needed to maintain thesulphur-carbon reaction in the reduction chamber is obtained by'burningsulphur to produce sulphur dioxide which itself is employed as a sourceof sulphur in the reduction process. The amount of heat needed tomaintain the reaction is introduced into the reaction zone along withthe reactant gases and consequently a large reaction chamber cheaplyconstructed of a steel shell and refractory lining may be employedinstead of the expensive prior art apparatus previously mentioned.

I claim:

1. The method for making carbon bisulphide from sulphur dioxidecontaining gas initially at temperature less than that necessary toeffect combination of sulphur of said sulphur dioxide `bisulphide,introducing said sulphur dioxide containingv gas and Vsaid sulphurcombustion prod'- ucts into a reaction zone containing ka body ofcarbonaceous material, effecting combination in said zone of. ysulphur.ofsaid sulphur dioxide and sulphur ofv said sulphur combustion productswith carbon of the carbonaceous material to produce carbon bisulphide,and recovering carbon bisulphide.

2. The method for making carbon bisulphide from sulphur dioxidecontaining gas initially at temperature less than that necessary toeffect combination of sulphur of said sulphur dioxide and carbon toproduce carbon bisulphide which comprises burning, with oxygen, sulphurin at least such amount that when burned with said oxygen and thecombustion products formed are mixed with said sulphur dioxidecontaining gas the temperature of the resulting gas mixture is raisedsuiciently high to effect combination of sulphur and carbon to producecarbon bisulphide, said burning of sulphur being eiected With notsubstantially more oxygen than necessary to convert the sulphur thusburned to sulphur dioxide, introducing said sulphur dioxide containinggas and said sulphur combustion products into a reaction Zone containinga body of carbonaceous material, effecting combination in said Zone ofsulphur of said sulphur dioxide and sulphur of said sulphur combustionproducts with carbon of the carbonaceous material to produce carbonbisulphide, and recoverlng carbon bisulphide. Y

3. 'I'he method for making carbon bisulphide from sulphur dioxidecontaining gas initially at temperature less than that necessary toeffect combination of sulphur of said sulphur dioxide and carbon toproduce carbon bisulphide which comprises introducing into said gassulphur and sulphur combustion supporting oxygen, said sulphur being atleast such amount that when burned the temperature of the resulting gasmixture is raised sufficiently high to effect combination of sulphur andcarbon to produce carbon bisulphide, burning said sulphur with saidoxygen, introducing the resulting gas mixture comprising said sulphurdioxide containing gas and the sulphur combustion products formed into areaction Zone containing a body of carbonaceous material, electingcombination in said zone of sulphur of said sulphur dioxide and sulphurof said sulphur combustion products with carbon of the carbonaceousmaterial to produce carbon bisulphide, and recovering carbon bisulphide.

4. The method for making carbon bisulphide from sulphur dioxidecontaining gas initially at temperature less vthan that necessary toeffect combination of sulphur of said sulphur dioxide and carbon toproduce carbon bisulphide which comprises introducing into said gassulphur and sulphur combustion supporting oxygen, said sulphur being inat least such amount that when burned the temperature of the resultinggas mixture is raised suciently high to effect combination of sulphurand carbon to produce carbon bisulphide, said oxygen being in amount notsubstantially more than necessary to convert the sulphur thus burned tosulphur dioxide, burning said sulphur with said oxygen, introducing theY resulting gas mixture comprising said sulphur dioxide containing gasand the sulphur combustion products formed into a reaction zonecontaining a body of carbonaceous material, eiecting combination in saidzone of sulphur of said sulphur dioxide and sulphur of said sulphurcombustion products With carbon of the carbonaceous material to .producecarbon bisulphide, andrecovering carbon bisulphide.

5. The'method for'making carbon bisulphide which comprises decomposingsludge material, derived from sulphuric acid treatment of petroleumoils, by heating to form solid carbonaceous residue and a hot sulphurdioxide gas mixture containing condensing vapo-rs, cooling the hot gasmixture to condense the bulk of the condensible vapors and formingrelatively cool concentrated sulphur dioxide gas, introducing saidcarbonaceous material into a reaction zone, and burning, with oxygen,sulphur in at least such amount that When burned with said oxygen andthe combustion products formed are mixedwith said sulphur dioxide gasthe temperature of the resulting gas mixture is raised suiciently highto eiect combination of sulphur and carbon to produce carbon bisulphide,introducing said sulphur dioxide gas and said sulphur combustionproducts into said reaction zone, effecting com# bination in said zoneof sulphur of said sulphur dioxide and sulphur of said sulphurcombustion products with carbon of the carbonaceous material containingnot more than about 3% volatile matter to produce carbon bisulphide, andrecovering carbon bisulphide.

6. The method for making carbon bisulphide Which comprises decomposingsludge material, derived from sulphuric acid treatment of petroleumoils, by heating to form solid carbonaceous residue and a hot sulphurdioxide gas mixture containing condensing vapors, cooling the hot gasmixture to condense the bulk of the condensible vapor and formingrelatively cool concentrated sulphur dioxide gas, introducing saidcarbonaceous material into a reaction zone. and introducing into saidsulphur dioxide gas sulphur and sulphur combustion supporting oxygen,said sulphur being in at least such amount that when burned thetemperature of the resulting gas mixture is raised sufficiently high toeffect combination of sulphur and carbon to produce carbon bisulphide,burning said sulphur with said oxygen, introducing the resulting gasrmixture comprising said sulphur dioxide gas and the sulphur combustionproducts formed into said reaction Zone, effecting combination in saidZone of sulphur of said sulphur dioxide and sulphur of said sulphurcombustion products With carbon of the carbonaceous material containingnot more than about 3% volatile matter to produce carbon bisulphide, andrecovering carbon bisulphide.

'7. The method for making carbon bisulphide which comprises decomposingsludge material, derived from sulphuric acid treatment of petroleumoils, by heating to form solid carbonaceous residue and a hot sulphurdioxide gas mixture containing condensing vapors, cooling the hot gasmixture to condense the bulk of the condensible vapors and formingrelatively cool concentrated sulphur dioxide gas, introducing saidcarbonaceous material into a reaction zone and introducing into saidsulphur dioxide gas sulphur and sulphur combustion supporting oxygen,said sulphur being in at least such amount that when burned thetemperature of the resulting gas mixture is raised sufficiently high toeffect combination of sulphur and carbon to produce carbon bisulphide,said oxygen being in amount not substantially more than that necessaryto convert the sulphur thus burned 'DO of said sulphur combustionproducts with carbon Vof the carbonaceous material containing not morethan about 3% volatile matter to produce carbon bisulphide, andrecovering carbon bisulphide. Y

' HENRY F. MERRIAM.

